Adjustable coupling device

ABSTRACT

A coupling device for placing at one end of a shaft (21), comprising a hub (40) to be mounted on and axially locked relative to the shaft (21), the shaft (21) being surrounded by a hollow cylinder (34). The hollow cylinder (34) and the shaft (21) are locked in their relative adjusted angular positions by a locking washer (70) held against the front surface (35) of the hollow cylinder (34) by a locking screw (61) centered on the axis (20) of the shaft (21) axially holding the hollow cylinder (34) against the hub (40), the device being preassembled to form a sub-assembly.

CROSS REFERENCE TO RELATED APPLICATION

This is the 35 USC 371 national stage of international applicationPCT/FR96/00880 filed on Jun. 11, 1996 which designated the United Statesof America.

FIELD OF THE INVENTION

The present invention concerns a device for coupling a hollow cylinderto a shaft, designed to be mounted at the end of said shaft, therelative angular position of the cylinder and of the shaft beingadjustable.

BACKGROUND OF THE INVENTION

A device of this kind is of the type described in document EP-A-0 148794. The device of the above document is satisfactory but the device isgenerally mounted on a shaft that is adapted to receive it and it is notalways easy to mount it, its components parts having to be mounted oneafter the other.

SUMMARY OF THE INVENTION

An aim of the present invention is to propose a device of the above kindadapted to be mounted at the end of an existing shaft and whichadditionally constitutes a subassembly that is easy to mount at the endof said shaft, in the manner of a pulley-wheel, for example.

In accordance with the invention, a device for coupling to a shaftadapted to be placed at the end of said shaft, includes a hub adapted tobe mounted on and keyed axially to said shaft, said shaft beingsurrounded by a hollow cylinder, locking in their adjusted relativeangular position of the hollow cylinder and the shaft being assured by aretaining washer pressed against the front face of the hollow cylinderby means of a retaining screw centered on the axis of the shaft pressingthe hollow cylinder axially against the hub, an annular ring centered onthe axis of the shaft being surrounded by the hollow cylinder andmovable axially, being adapted, during said axial movement to adjust therelative angular position of the hollow cylinder and the shaft, thedevice being pre-assembled to constitute a subassembly.

Advantageously, the device is pre-assembled by means of a bracket; thebracket is axial; the bracket is transversal; alternatively, the deviceis pre-assembled by means of a nut adapted to be cut easily cooperatingwith the thread of the retaining screw.

Advantageously, the annular ring has longitudinal splines on its insidesurface whereby it can be constrained to rotate with said shaft whilstbeing movable axially and at least one tooth with helical flanks on itsoutside surface, said hollow cylinder having at least one splinerecessed into its inside surface and adapted to receive said at leastone tooth of the annular ring, the flanks of said spline being helicaland in corresponding relationship with the helical flanks of said atleast one tooth of the annular ring.

Alternatively, the annular ring has helical splines on its insidesurface whereby it can be constrained to rotate with said shaft whilstbeing movable axially and at least one tooth with straight or reversepitch flanks on its outside surface, said hollow cylinder having atleast one spline recessed into its inside surface adapted to receivesaid at least one tooth of the annular ring, the flanks of said splinebeing straight or of reverse pitch and in corresponding relationshipwith the straight or reverse pitch flanks of said at least one tooth ofthe annular ring.

Advantageously, the device is pre-assembled by the retaining screw.

Alternatively, the annular ring has on one side, i.e. on its insidesurface or on its outside surface, longitudinal splines and, on theother side, at least one tooth with helical flanks, said hollow cylinderor said hub having at least one spline adapted to receive said at leastone tooth of the annular ring, the flanks of said spline being helicaland in corresponding relationship with the helical flanks of said atleast one tooth of the annular ring, said longitudinal splines enablingthe annular ring to be mounted on the part, either the hollow cylinderor the hub, that does not include said at least one spline but insteadlongitudinal splines complementary with the longitudinal splines of theannular ring.

Advantageously, said hub is also locked to the shaft in a predeterminedangular position so as to rotate with the shaft; the axial locking ofthe hub is obtained by means of a bearing surface on the shaft havingsplines that extend the splines of the shaft and that cooperate withcorresponding splines of the hub likewise extending its splines.

Preferably, for the axial displacement of the annular ring, an annulardrive screw carries a helical thread which cooperates with a helicalthread on the portion of the surface of the part without the splines,either the hollow cylinder or the hub, that carries the at least onespline, said annular ring being coupled in translation to said annulardrive screw; a transverse abutment limits the axial travel of theannular screw; the annular screw is slit and its thread isadvantageously a single thread starting from one side of said slit andending at the other side; the annular screw is preferably braked; thisis achieved by the use of an annular screw that is not rigorouslycircular at rest but deformed radially and mounted elastically, forexample.

Preferably there is a plurality of teeth with helical flanks, polarizermeans being provided for correct mounting of the device on the shaft.

Advantageously the ends of the threaded areas are circumferentially inline with or at a distance from the helical flanks of the rim on aradius at least equal to the radius of the thread root; said ends areinclined to said flanks, a radius being provided at the root of theteeth.

Preferably, the hub is mounted on a conical part of the shaft by meansof a key the edge of which is parallel to the generatrix of said conicalpart, the bottom of the key slot having a part parallel to the axis ofthe shaft followed by a part parallel to said generatrix.

Advantageously, the hub has at least one radial lug with a thread toreceive a screw passing through a circumferential opening in the rim.

Preferably, the retaining washer is slightly conical when at rest andplane after clamping.

Alternatively, the retaining washer is plane when at rest and slightlyconical after clamping, the front face of the hollow cylinder being alsoslightly conical.

Advantageously, the retaining washer has at least one opening for anadjuster tool.

To increase the driving torque transmitted via the bearing face of thehollow cylinder to the hub, the surfaces of the parts in contact arepreferably coated with a friction material; alternatively, a brake discis disposed between the parts.

In one application of the invention, the cylinder is carried by thedrive unit of a windshield wiper arm.

In another application, the hollow cylinder is carried by the rim of apulley-wheel; the at least one tooth with helical flanks of the annularring is at the start of adjustment in the position corresponding to themaximum angular lag of the shaft, the helical flanks of the hollowcylinder have a lefthand thread and the annular screw having a righthandthread.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will become more apparentfrom a reading of the following description with reference to theaccompanying drawings, in which:

FIG. 1 is a view in axial section of a device in accordance with theinvention mounted at the end of a shaft before adjustment and equippedwith a mounting bracket;

FIG. 2 is a fragmentary view in cross-section taken along the lineII--II in FIG. 1;

FIG. 3 is a view of the device from FIG. 1 in axial section afteradjustment;

FIG. 4 is a perspective view of an adjuster key for adjusting the deviceof FIGS. 1 to 3;

FIG. 5 is a sectional view of the device from FIGS. 1 to 3 pre-assembledin a different way and shown to a smaller scale;

FIG. 6 is a fragmentary sectional view of the device from FIGS. 1 to 3pre-assembled in a further way and shown to a smaller scale;

FIG. 7 is a view in section taken along the line VII--VII in FIG. 6;

FIG. 8 is a sectional half-view of another device in accordance with theinvention;

FIG. 9 is a view to a smaller scale similar to that of FIG. 8 in axialsection taken along the line IX--IX in FIG. 10, and with an adjuster keyin place;

FIG. 10 is a fragmentary view in cross-section taken along the line X--Xin FIG. 9;

FIG. 11 is a perspective view of an adjuster key for adjusting thedevice of FIGS. 8 to 10;

FIG. 12 is a variant of FIG. 9;

FIG. 13 is a variant of the device from FIGS. 1 to 3, for a differentapplication, in axial section taken along the line XIII--XIII in FIG.14;

FIG. 14 is a fragmentary view in cross-section taken along the lineXIV--XIV in FIG. 13;

FIG. 15 is a diagram showing a portion of the distributor means of anautomobile vehicle engine;

FIG. 16 is a fragmentary view in axial section of another variant of thedevice of the invention;

FIG. 17 is a fragmentary view in cross-section of a variant of thedevice from FIGS. 8 to 10;

FIG. 18 is a fragmentary view in axial section of a variant of thedevice from FIGS. 8 to 10; and

FIG. 19 is a fragmentary view in cross-section taken along the lineXIX--XIX in FIG. 18.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The coupling device of the invention has many and varied applications,in particular in the automobile industry.

Take the case of an automobile vehicle windshield wiper, for example:the windshield wiper blade is carried by a windshield wiper arm thatreciprocates; to be more precise, the arm is pivoted to a drive unitattached to the end of a drive shaft, a spring disposed between the armand the drive unit pressing the wiper onto the windshield; for fasteningthe drive unit to the drive shaft, the latter has a splined portion,generally conical, extended by a screwthreaded shaft end; the splinedportion receives the drive unit, which incorporates a correspondingbore, and a nut is screwed onto the screwthreaded end of the shaft;after the nut is tightened the splines on the splined portion areembedded in the drive unit to fasten the drive unit rotationally to thedrive shaft.

The angular position of the drive unit relative to the drive shaftdetermines the sweep of the wiper on the windshield; the drive unit musttherefore be positioned correctly; this is not easily achieved;furthermore, if it is not right on the first attempt, it is even moredifficult thereafter because the bore in the drive unit has been markedby the splines on the drive shaft.

The coupling device of the invention overcomes these drawbacks.

Referring to FIGS. 1 to 3, the end of a drive shaft 21 leaving a bearing27 and reciprocating in rotation is adapted to drive reciprocatingrotation of a drive unit 28 to which a windshield wiper arm (not shown)is pivoted.

The drive unit 28 includes a hollow cylinder 34; in the present contexta hollow cylinder means some kind of sleeve or ferrule; one axial end ofthe hollow cylinder 34 bears axially against a hub 40, being centered byan annular bearing surface 53 on the hub 40, fitted over the shaft 21until it abuts axially against a bearing surface 25 on the shaft 21, forexample a conical bearing surface; longitudinal splines 51 are formed inthe outside wall of the end portion of the shaft 21, between the latterand the bearing surface 25; the inside bore by means of which the hub 40is mounted on the end of the shaft 21 is provided with longitudinalsplines 52 cooperating with longitudinal splines 51 formed on theoutside surface of the end of said shaft centering the hub 40 which inturn centers the hollow cylinder 34 by virtue of its bearing surface 53.

As shown here, the bearing surface 25 of the shaft 21 is advantageouslyprovided with splines that extend the splines 51 and that cooperate withcorresponding splines of the hub 40 that extend its splines 52 in asimilar manner.

The end of the shaft 21 is hollow; it is provided with a screwthread 57which opens to the exterior via a smooth bore 58 axially forward of thebearing surface 25; the diameter of the smooth bore 58 is greater thanthat of the screwthread 57 and its outlet end is flared.

The screwthread 57 is adapted to receive a complementary screwthread 60on the outside periphery of the end of the shank 62 of a retaining screw61 having a head 63 with a polygonal recess 65 for turning the screw 61.

The head 63 of the screw 61 is in the form of a flange and its rear face66 is adapted to cooperate with a retaining washer 70 in turn adapted tocooperate with the front face 35 of the hollow cylinder 34; when thescrew 61 is tightened in the shaft 21 the retaining washer 70 is at anaxial distance from the end of the shaft 21 and the hollow cylinder 34is therefore pressed onto the hub 40 which in turn bears axially on theshaft 21.

The front face 35 of the hollow cylinder 34 is advantageously flanked byan annular rim 59 to center the retaining washer 70 via its outsideperiphery; the retaining washer 70 supports and centers the retainingscrew 61 which has a cylinder bearing surface 67 having a diameter lessthan that of the head 63 but greater than that of the shank 62 and withwhich the central bore 73 in the retaining washer 70 cooperates.

The radial gap between the end of the shaft 21 and the hollow cylinder34 accommodates a device for adjusting the relative angular position ofthe hollow cylinder 34 and the shaft 21.

Longitudinal splines 81 formed on the inside surface of an annular ring80 are interleaved with the longitudinal splines 51 on the shaft 21. Theoutside periphery of the ring 80 carries teeth 82 with helical flanks83, 84 and a broad pitch adapted to cooperate with respectivecorresponding helical flanks 38, 39 of splines 36 formed on the insidesurface of the hollow cylinder 34.

The portions of the inside surface of the hollow cylinder 34 between thesplines 36 carry a narrow pitch helical screwthread 29 that cooperateswith the corresponding outside screwthread 56 of an annular drive screw55 coupled in translation to the ring 80 by a heel-piece 94 housed in anannular groove 85 on the ring 80.

In the embodiment shown, the groove 85 is cut annularly; it could beformed by front and rear transverse abutments offset successively andcircumferentially, of course, for example to facilitate manufacture ofthe ring 80 by a molding process.

From the foregoing description it is evident that the angulardisplacement of the drive unit 28 relative to the shaft 21 is obtainedby turning the annular drive screw 55; to this end the latter has at thefront one or more radial notches 95, for example three radial notches 95at 120°, adapted to receive the ends of adjuster pins 91 of an adjusterkey 90 (see FIG. 4) consisting of a disk 93 to which the pins 91 areperpendicular and which has at its center a square hole 92 adapted toreceive the square end of an operating tool, if necessary; as shown inchain-dotted line in FIG. 3, correct positioning of the key 90, inparticular of the ends of the pins 91 in the notches 95, is facilitatedby the fact that the head 63 of the screw 61 has a cylindricalperipheral surface the diameter of which is such that it is inscribedperfectly in the volume encompassed by the adjuster pins 91 and, whenthe latter are in line with the head 63 parallel to its axis, they areradially in line with the notches 95; the retaining washer 70 naturallyhas openings 74 at 120° for the adjuster pins 91 to pass through.

To facilitate mounting of the drive unit 28 on the shaft 21, the annularring 80 and its annular drive screw 55 having been installed inside thehollow cylinder 34, the ring 80 being in a median axial positionrelative to the splines 36, as shown in FIG. 1, the hub 40, the washer70 and the screw 61 are fitted and held in place by an elastic axialbracket 96, made of plastics material, for example, urging the hub 40and the head 63 of the screw 60 on which its bears towards each other inthe axial direction; the head 63 positions it transversely in twoperpendicular planes. A passage 97 in the bracket 96 enables theresulting assembly to be threaded onto the shaft 21. This provides anassembly ready to be mounted on the shaft 21, the screwthread 60 showingon the inside of the bracket 96 and providing a lead-in for mounting theassembly on the shaft 21.

To this end, it is easy to thread the splines 52 of the hub 40 ontothose 51 of the shaft 21, by pivoting the drive unit 28; then, afterorienting the wiper-holder arm, and therefore the drive unit 28, asclose as possible to its intended end of travel position on thewindshield, the assembly is pushed towards the right, as seen in FIG. 1,and the retaining screw 61 is tightened by passing the tightening toolthrough a passage 98 in the bracket 96; the screw 61 is then loosened,for example by one quarter-turn, to release the retaining washer 70.

The bracket 96 is removed, a slot 99 opening into the passage 97enabling this; the width of the slot 99 is advantageously less than thediameter of the shaft 21 to prevent it falling off accidentally.

Precise adjustment of the position of the drive unit 28 relative to theshaft 21 can be facilitated by ensuring that during the adjustment thedrive unit 28 turns in the same direction as that in which the adjusterkey 90 is turned; to achieve this, all that is required is that thepitch of the helical flanks 38, 39-83, 84 for the ring 80 be in theopposite direction to that of the threads 29-56 for the annular screw55.

The screw 61 is then tightened; the washer 70 has some elasticity; itcan be slightly conical at rest and plane after clamping; in this case,the bearing surface 35 is plane; of course, the opposite arrangement isequally feasible, the bearing surface 35 then being conical with a coneangle that corresponds to that of the deformed washer 70 after clamping.

As a safety measure, to prevent the annular screw 55 moving forwardlybeyond the face 35 of the hollow cylinder 34 during the adjustment, atransverse abutment 36A limits the axial travel of the annular screw 55;in the embodiments shown in the figures the abutment 36A is the axialbottom of the splines 36 which are blind; as an alternative to this theabutment 36A is dispensed with and it is the thread 29 itself thatdefines the end of travel of the annular screw 55.

FIG. 5 shows the device from FIGS. 1 to 3 pre-assembled differently, andto a smaller scale; the bracket 96 is replaced by a nut 216 that can becut easily, for example a nut made from plastics material, mounted onthe screwthread 60 of the retaining screw 61; the combination of theretaining washer 70, the hollow cylinder 34 and the hub 40 is thereforemaintained axially between the head 63 of the retaining screw 61 and thenut 216; the latter incorporates radial cuts 217, for example threeradial cuts distributed circumferentially, forming areas 218 that can becut easily; the nut 216 has a conical entry 221 so that when theassembly is offered up in front of the shaft 21 and pushed towards thelatter the end of said shaft 21 splits the nut 216, into three segmentsin this example, because of the conical entry 221; all that then remainsis to screw in the retaining screw 61.

In FIGS. 6 and 7 pre-assembly is effected by means of a bracket 196,which is a transverse bracket in this example, for example made fromplastics material, in the form of a plate having two flanges 201, 202defining a notch 203 with a circular bottom the diameter of which isequal to the root diameter of the screwthread 60 of the retaining screw61 and the width of the entry of which is less than said diameter; atthe end opposite that having the notch 203, the transverse bracket 196has holding means, in this example a ring 204; in this way the assemblyis held axially between the head of the retaining screw 61 and thetransverse bracket 196 clipped to the screwthread 60 of said screw;after inserting the end of the screwthread 60 into the shaft 21, allthat remains is to remove the transverse bracket 196 radially, by meansof the ring 204, and to screw in the retaining screw 61.

In a variant of the device from FIGS. 1 to 3 that is not shown, theannular ring 80 has helical splines on its inside surface, so that itcan be rotationally fastened to said shaft whilst being mobile in theaxial direction, and at least one straight-flank or reverse pitch toothon its outside surface, the hollow cylinder having at least one splinerecessed into its inside surface adapted to receive said at least onetooth of the annular ring, the flanks of said spline being straight orof reverse pitch and in corresponding relationship to the straight orreverse pitch flanks of said at least one tooth of the annular ring.

One application of the device in accordance with the invention has beendescribed in which the shaft is a driving shaft; of course, theinvention applies equally well to the situation in which the shaft is adriven shaft, as in a different application described next.

An automobile engine includes distributor means that include a driveshaft, i.e. the crankshaft, and driven shafts adapted to drive otherunits, for example, the camshaft and the drive shaft of a fuel pump suchas a diesel injection pump.

The driven shafts are driven by the drive shaft through gears at theends of the shafts and coupled kinematically or by a chain or a notchedbelt linking notched pulley-wheels provided at the ends of said shafts.

These driven pulley-wheels and gears must naturally be rigorouslypositioned or immobilized relative to the drive shaft; incorrect lockingof the camshaft impacts on pollution by the engine emission gases, forexample, on fuel consumption, on power output and, more generally, onits behavior overall; incorrect locking of the injection pump driveshaft likewise has a similar impact.

Given the large number of component parts included in a distributorsystem and the manufacturing tolerances for such parts, it is impossibleto achieve proper locking by construction.

It can be effected by positioning the various parts using shims andmeasuring instruments. These methods are time-consuming and thereforecostly.

FIG. 15 is a schematic representation of the distributor system of avehicle engine formed by a belt 110 linking a drive pulley-wheel 111fastened to a drive shaft 121 to three driven pulley-wheels 112, 113 and114 respectively fastened to an injection pump shaft 122, a camshaft 123and an oil pump shaft 124; rollers 115 and 116 tension the belt 110.

Referring to FIGS. 8 through 10, the pulley-wheel 112 of the injectionpump comprises two coaxial parts, a rim 130 and a hub 140; the rim 130has at its periphery teeth 131 adapted to cooperate with the notches ofthe notched belt 110.

The hub 140 has a central conical bore 141 received by a correspondingconical bearing surface 125 on the shaft 122, the conical bore 141 beingclamped onto the conical bearing surface 125 by a nut 117 screwed ontothe screwthreaded end of the shaft 122, the base 118 of the nut 117bearing on the front transverse face 142 of the hub 140 flanking theconical bore 141; a key 127 assures angular pre-positioning androtational fastening between the hub 140 and of the shaft 122.

The transverse face 142 of the hub 140 incorporates an annular recess143 the larger diameter inside cylindrical surface of which extendsaxially beyond the transverse face 142 and the base 118 of the nut 117,flanking axially on the same side as the axis 120 of the shaft 122 askirt 144 whose greater diameter cylindrical outside wall extendsaxially towards the rear, beyond the recess 143, as far as a transversewall 145 extended in its upper part by a cylindrical axial rim 146extended by a conical bearing surface 147; the hub 140 is delimited onthe side opposite that with the recess 143 by a rear transverse face148.

The rim 130 includes a ring 132 with teeth 131 at its outside peripheryand an internal radial web 133 connecting the ring 132 to a hollowcylinder 134 coaxial with the axis 120 extending axially relative to theweb 133 from the same side as the skirt 144, at a radial distance fromsaid skirt 144, the front transverse end face 135 of the cylinder 134extending beyond the front transverse end face 149 of the skirt 144.

The rim 130 has at the rear a conical bearing surface 137 complementaryto the conical bearing surface 147 on the hub 140 with which itcooperates when the rim 130 and the hub 140 are assembled together, asshown in FIG. 8.

This assembly is effected as follows.

The skirt 144 of the hub 140 has an internal screwthread 150 adapted toreceive a complementary screwthread 160 on the outside periphery of theshank 162 of an annular screw 161 having a head 163; the inside bore 165of the screw 161 surrounds the nut 117 at a distance and is polygonal inshape for turning the screw 161.

The head 163 of the screw 161 is in the form of a flange having anoutside diameter greater than the diameter of the shank 162 and isadapted to cooperate with a retaining washer 170 itself adapted tocooperate with the front face 135 of the rim 130. In the example shownthe retaining washer 170 has an external part 171 and an internal part172; the retaining washer 170 is substantially elastic; at rest, itsoutside part 171 and its inside part 172 are both frustoconical, theconcave side of the washer 170 facing the face 135 of the hollowcylinder 134, as shown in chain-dotted line in FIG. 9; to fasten the rim130 to the hub 140 it is mounted on the hub 140 so that its conicalbearing surface 137 cooperates with the conical bearing surface 147 ofthe hub 140; the washer 170 is fitted, and then the annular screw 161;on tightening the latter, the conical bearing surfaces 137 and 147 arepressed together; the head 163 of the annular screw 161 has a conicalface 166 which, on completion of tightening, espouses the shape of theinside part 172 of the washer 170, its outside part 171 deforming untilit is perpendicular to the axis 120, so espousing the shape of the fronttransverse face 135 of the cylinder 134.

The radial gap between the skirt 144 and the hollow cylinder 134 housesa device for adjusting the relative angular position of the rim 130 andthe hub 140 and therefore the shaft 122.

The skirt 144 of the hub 140 has on its inside surface longitudinalsplines 151 between which are interleaved corresponding longitudinalsplines 181 on the inside surface of an annular ring 180 defining lugs187 between them. At its outside periphery the ring 180 has teeth 182with helical flanks 183, 184 (see FIG. 10) with a broad pitch adapted tocooperate with respective corresponding helical flanks 138, 139 ofsplines 136 on the inside surface of the hollow cylinder 134 of the rim130. The pitches of the helical flanks that cooperate with each other,e.g. 138-183 and 139-184, are advantageously not strictly identical, butvery slightly different so that there is a lead angle for the drivingpiece.

The portions of the inside surface of the hollow cylinder 134 betweenthe splines 136 carry a narrow pitch helical screwthread 129 cooperatingwith the corresponding outside screwthread 156 of an annular drive screw155 coupled in translation to the ring 180 by a heel-piece 157 on itaccommodated in a groove 185 in the ring 180. The groove 185 is in anaxial extension of the ring 180, the annular screw 155 being split tofacilitate insertion of the heel-piece 157 into the groove 185.

Three positions of the tooth 182 of the ring 180 are shown inchain-dotted line in FIG. 8: the position X at the start of theadjustment corresponding to the maximum angular lag of the shaft 122,the position Y in the middle of the adjustment corresponding to thetheoretical position of a non-adjustable pulley-wheel, and the positionZ at the end of the adjustment corresponding to the maximum angularadvance of the shaft 122.

For a static adjustment, with the engine stopped, the correct positionof the shaft 122 is detected, for example, using a comparator monitoringthe angular displacement of the reference point on the shaft relative toa known point, for example the body of a diesel injection pump.

The angular displacement of the shaft 122 is obtained by rotating theannular screw 155 by means of an adjuster key 190 described below tomove the ring 180 in translation in the direction X Z until thecomparator shows the required value. Any other monitoring means can ofcourse be used to check correct positioning of the shaft, for examplebringing two dots or two orifices or two grooves into alignment.

Referring to FIG. 11, the adjuster key 190 comprises a disk 193 carryingthree adjuster pins 191 adapted to cooperate with the notches 195 of theannular drive screw 155 through the openings 174 of the retaining washer170; to facilitate the use of the key 170, it also carries threecentering pins 194, longer than the adjuster pins 191, adapted tocooperate with the outside periphery of the washer 170, as shown in FIG.9, to facilitate centering of the key 190 before insertion of theadjuster pins 191. The three centering pins 194 can of course bereplaced by a cylindrical skirt.

Throughout the adjustment of the driven shaft the rim 130 must maintainthe tension in the tensioned runs of the belt in order not to modify thedistance between the point A and the point B (FIG. 15).

The pulley-wheel 112 constitutes a complete drive device assembled withminimum play but not locked by the screw 161 and ready for fitting andadjustment. It is mounted on the shaft by means of its hub 140 which isfastened to the shaft 122 by clamping it thereto using the nut 117.

The rim 130 is immobilized by the belt in the theoretical position,marked relative to the point B. The part of the belt between A and B,known as the taut run, is tensioned to eliminate spread due to the belt.

To rotate the hub 140 clockwise, the ring 180 is placed in position X(FIG. 9), the helical flanks 138, 139 of the rim 130 advantageouslyhaving a lefthand thread for reasons explained below.

Of course, the washer 170 is free to rotate during adjustment tominimize the force to be applied to the adjuster key 190 and avoidrotating the screw 161.

Given the tension in the belt 110, the ring 180 and the annular screw155 offer some resistance to axial displacement on the hub 140. Becausethe ring 180 moves from X to Z during the adjustment, the rim 130 tendsto move from Z to X, due to the thrust of the annular screw 155;accordingly, during the adjustment, the rim 130 is pressed onto thebearing surface 147 of the hub 140, so allowing the washer 170 to rotatefreely, with minimum play.

The thread of the annular screw 155 is advantageously a righthand threadand the screw turns anticlockwise: the tension in the taut runs of thebelt 110 is therefore maintained; moreover, anticlockwise frictionbetween the annular screw 155 and the ring 180 holds the latter pressedonto the helical flanks 138 of the rim. The ring 180 is then drivenclockwise and the flanks 188 of its lugs 187 bear on the flanks 152 ofthe longitudinal splines 151 of the hub 140 driven clockwise.

By virtue of these provisions, the adjustment successively eliminatesplay between all the component parts of the pulley-wheel 112:

the annular screw 155, turning anticlockwise, bears on its thread flank156 which is pressed onto the flank of the thread 129 of the rim. Thiscontact is favored by the pressure in the direction Z X of the adjusterkey 190, the ends of the pins 191 of which bear on the bottom of theadjuster notches 195 of the annular screw 155;

the annular screw 155 tending to move away from the ring 180, the frontbearing surface on its heel-piece 157 comes into contact with the frontbearing surface of the groove 185 in the angular adjustment ring 180that begins to move from X to Z in the axial direction;

the ring 180, braked by the hub 140 in its movement in translation fromX to Z, tends to hold the face 137 of the rim in contact with the face147 of the hub, via the annular screw 155;

contact between the helical flanks 138 and 183 is maintained by theanticlockwise rotation of the annular screw 155, which also preventsaltering of the tension in the belt if the adjustment torque is high;

the ring 180, in addition to its axial displacement, then rotatesclockwise, given the direction of the helical flanks 138 and 183, andthe flanks 188 of its lugs 187 come to bear on the flanks 152 of thesplines 151 on the hub 140.

It is only from this moment, with play and spread eliminated, that theadjustment begins.

As stated above, the pitch of the helical flanks is relatively broad andthat of the thread of the annular screw 155 is relatively narrow. Forexample, if the screwthread has a pitch of 3 and the helical flanks havea pitch of 540, this represents a ratio of 1/180, i.e. 180° angulardisplacement of the annular screw 155 procures an angular displacementof 1° of the ring 180 and therefore of the shaft 122. Thisdemultiplication effect, despite friction forces, reduces by a factor ofaround 3 or 4 the force that would have to be applied if the shaft 122were turned directly. This avoids the need to use rotation assistancethat would inevitably degrade the adjustment.

The screw 161 is advantageously braked by a screw brake, for example acoating on its thread or (as shown here) a corrugated split ring 109, sothat it does not turn during the adjustment, as it would then to tend toclamp the rim 130 onto the hub 140 and the adjustment would no longer bepossible. The brake 109 also defines a minimum adjustment play that canbe controlled with great precision, for example: tightening of the screw161 to approximately 1.5 m.kg, then slackening by 25° to 30°,representing a play of approximately 0.1 mm, allowing the washer 170 torotate between the bearing face 166 of the screw 161 and the bearingface 135 of the rim 130.

All the pulley-wheels are therefore delivered to the production linewith this same adjustment, which cannot vary in transmit because thescrew 161 is braked. Of course, the angular ring 180 can be moved toposition X bearing on the hub 140, if desired, so extending the assemblyand thereby immobilizing the retaining washer 170, the annular screw 155and the ring 180.

It is possible to simplify the machining of the hollow cylinder 134 ofthe rim 130 and that of the annular ring 180, in particular to avoid theneed for deburring after cutting the thread 129 and eliminating thesharp angle at the foot of the teeth 182 of the ring 180 which couldconstitute a weak point from which cracking could start; referring toFIG. 17, the ends 169 of the threaded areas are at a circumferentialdistance 168 from the helical flanks 138, 139 of the rim 130, at aradius at least equal to the radius 179 of the thread root; the ends 169are inclined to the flanks 138, 139 and produce a radius 186 at the footof the teeth 182; note that this inclination also favors the entry ofthe thread-cutter into the material and reduces burrs at the exit.

The shank 162 of the retaining screw 161 advantageously has on the sameside as the axis 120 a rim defining a bearing surface 164 (FIG. 8) whichis slightly conical in this example, with which a corresponding bearingsurface 119 on the base 118 of the nut 117 cooperates; accordingly, whenthe nut 117 is unscrewed it serves as an extractor for the pulley-wheel112.

The presence of a nut of this kind may impede correct fitting of thepulley-wheel 112 to the shaft 122; to facilitate finding the key slot inthe hub 140 blind, as shown in FIGS. 18 and 19, the bottom 502 of theslot is parallel to the axis of the shaft, the key 127 being placed sothat its rectilinear edge is parallel to said axis; if it is requiredfor the hub 140 of this pulley-wheel to be also mountable on a shaft inwhich the edge of the key is parallel to the top generatrix, as seen inFIG. 18, of the conical part 125 of the shaft, all that is required isto provide a slot bottom 502 parallel to the axis of the shaft followedby a slot bottom 501 parallel to said generatrix.

If the annular ring 180 comprises only one tooth 182 and cooperates withone only longitudinal spline 151 of the hub 140, no mounting error ispossible when the pulley-wheel is mounted on the shaft 122; if this isnot the case, it is advantageous to provide polarizer means; such meansare obtained, for example, by making one of the teeth wider or longerthan the others or offsetting one tooth relative to the others.

In the FIG. 12 variant it is the hollow cylinder 234 of the rim 230 thathas internal longitudinal splines 251 while the hub 240 carries thesplines 236 with helical flanks and the outside screwthread 229, theannular ring 280 and the annular screw 255 being designed accordingly;the hollow cylinder 234 is centered on a recess 253 of the hub 240flanked by a bearing surface 247, a transverse bearing surface in thisexample, with which a transverse bearing surface 237 of the rim 230cooperates abutment-fashion; in this example the retaining washer 270 issimilar to the washer 70 from FIG. 1 and plane after clamping, theannular retaining screw 261 having a transverse application face 266.The drive torque being assured by cooperation of the bearing surfaces237 and 247, it can be improved by disposing a coating or a washerbetween the latter to increase the coefficient of friction.

In the variant of FIGS. 13 and 14 the arrangement is of the kinddescribed with reference to FIGS. 1 to 3 in the sense that it is theshaft 322, in this example a driven shaft, which carries the annularring 380, sliding by virtue of a longitudinal spline 351, coupling tothe annular drive screw 355, the hub 340 having a longitudinal tooth 352engaged in the spline 351; a ring 325 provides axial abutment of the hub340 relative to the shaft 322; in a different variant, the axialabutment is provided by means of a larger diameter portion of the shaft322, advantageously having an inclined front face.

The retaining screw 361 presses the washer 370 against the hollowcylinder 334 of the rim 330 which is itself pressed against the hub 340;if the pulley transmits a high torque it can be advantageous, as shownin the figures, to provide the hub 340 with at least one radial lug 375having a thread 378 to receive a screw 377 passing through acircumferential opening 376 in the rim 330; the circumferential extentof the opening 376 is sufficient to enable adjustment of the angularposition of the rim 330 relative to the hub 340 and thus relative to theshaft 322; the adjustment is made permanent by using a special screw377.

In the FIG. 16 variant the hub 440 is mounted on and covers the end ofthe shaft 422; to be more precise, on the side facing towards the shaft422 it has a housing with a cylindrical wall 487 matched to the diameterof the end of the shaft 422 and a bottom 486 adapted to abut on the endface 425 of the shaft 422; the hub 440 and the shaft 422 are positionedangularly and constrained to rotate together by an axial key 427 carriedby the hub 440; a retaining screw 461 passes through the retainingwasher 470 and the bottom of the hub 440 and is screwed into the shaft422; an elastic split ring 488 is housed in a groove 489 on the screw461 and retains the screw 461 axially in its exit direction by bearingon an annular recess in the hub 440; the hub 440, the rim 430, thewasher 470 and the screw 461 therefore constitute an assembly ready forfitting to the shaft 422.

What is claimed is:
 1. A subassembly comprising:a coupling device formounting at an end of a shaft, and comprisinga hub structured andarranged to be mounted on and axially keyed relative to said shaft; ahollow cylinder adapted to surround said shaft; an annular ringsurrounded by the hollow cylinder and axially movable, said annular ringbeing structured and arranged, during axial movement, to adjust arelative angular position of the hollow cylinder and the shaft; aretaining screw and a retaining washer for locking the hollow cylinderand the shaft in their adjusted relative angular position after thecoupling device has been mounted on the shaft by pressing the retainingwasher against a front face of the hollow cylinder with the retainingscrew, and the hollow cylinder against the hub; assembly means forassembling the coupling device, the retaining washer, and the retainingscrew as the subassembly, at least prior to mounting of the couplingdevice on the shaft.
 2. The subassembly according to claim 1, whereinthe assembly means comprise a bracket.
 3. The subassembly according toclaim 2, wherein the bracket is axial.
 4. The subassembly according toclaim 2, wherein the bracket is transversal.
 5. The subassemblyaccording to claim 1, wherein the assembly means comprise a nut adaptedto be cut easily, and cooperating with the thread of the retainingscrew.
 6. The subassembly according to claim 1, wherein the annular ringhas longitudinal splines on its inside surface for constraining itsrotation together with said shaft while being movable axially, and atleast one tooth with helical flanks on its outside surface; said hollowcylinder having at least one spline recessed into its inside surface andadapted to receive said at least one tooth of the annular ring; saidspline having flanks which are helical and in corresponding relationshipwith the helical flanks of said at least one tooth of the annular ring.7. The subassembly according to claim 1, wherein the annular ring hashelical splines on its inside surface for constraining its rotationtogether with said shaft while being movable axially, and at least onetooth with straight or reverse pitch flanks on its outside surface; saidhollow cylinder having at least one spline recessed into its insidesurface adapted to receive said at least one tooth of the annular ring;said spline having flanks which are straight or of reverse pitch and incorresponding relationship with the straight or reverse pitch flanks ofsaid at least one tooth of the annular ring.
 8. The subassemblyaccording to claim 1, wherein the assembly means comprise the retainingscrew.
 9. The subassembly according to claim 8, wherein the retainingscrew is annular and has a shank with a screwthread adapted to cooperatewith a complementary screwthread on the inside of a skirt of the hub,and a head in the form of a flange adapted to cooperate with theretaining washer.
 10. The subassembly according to claim 8, furthercomprising an elastic ring housed in a groove in the retaining screw,said elastic ring bearing on an annular recess in the hub.
 11. Thesubassembly according to claim 1, wherein the annular ring has on one ofits inside and outside surface, longitudinal splines and, on the otherof its inside and outside surface, at least one tooth with helicalflanks; at least one of said hollow cylinder and said hub having atleast one spline adapted to receive said at least one tooth of theannular ring; said spline having flanks which are helical and incorresponding relationship with the helical flanks of said at least onetooth of the annular ring; said longitudinal splines enabling theannular ring to be mounted on said at least one of the hollow cylinderand the hub, which does not include said at least one spline but insteadlongitudinal splines complementary with the longitudinal splines of theannular ring.
 12. The subassembly according to claim 11, wherein said atleast one tooth comprises a plurality of teeth with helical flanks, thesubassembly further comprising polarizer means for correctly mountingthe coupling device on the shaft.
 13. The subassembly according to claim1, wherein the retaining washer is slightly conical when at rest andplane after clamping.
 14. The subassembly according to claim 1, whereinthe retaining washer is plane when at rest, and slightly conical afterclamping; said hollow cylinder having a front face which is alsoslightly conical.
 15. The subassembly according to claim 1, wherein theretaining washer has at least one opening for an adjuster tool.
 16. Thesubassembly according to claim 1, wherein the hub has at least oneradial lug with a thread to receive a screw passing through acircumferential opening in a rim adapted to be pressed against the hub.17. Shaft fitted at one of its ends with the coupling device that ispart of the subassembly as claimed in claim 1, the hub of the couplingdevice being keyed to the shaft in a predetermined annular position torotate therewith.
 18. The shaft according to claim 17, wherein the hubis locked by a bearing surface of the shaft, said bearing surface havingsplines that extend splines of the shaft and cooperate withcorresponding splines of the hub.
 19. The shaft according to claim 17,wherein the hub is mounted on a conical part of the shaft by a keyhaving an edge which is parallel to a generatrix of said conical part;the hub including a key slot having a bottom, and the bottom of the keyslot having a first part parallel to the axis of the shaft followed by asecond part parallel to said generatrix.
 20. Windshield wiper armincluding a drive member coupled to the end of the shaft, the drivemember is carried by the hollow cylinder of the subassembly as claimedin claim
 1. 21. Pulley-wheel having a rim coupled to the end of theshaft, wherein said rim is carried by the hollow cylinder of thesubassembly according to claim
 1. 22. The pulley-wheel according toclaim 21, wherein the subassembly further comprises for the axialdisplacement of the annular ring, an annular drive screw carrying ahelical thread which cooperates with a helical thread on a surfacewithout splines of either the hollow cylinder or the hub, that carriesthere at least one spline, said annular ring being coupled intranslation into said annular drive screw, and wherein the hollowcylinder has helical flanks which have a lefthand thread, and thescrewthread of the annular drive screw has a righthand thread.
 23. Asubassembly comprising:a coupling device for mounting at an end of ashaft, and comprisinga hub structured and arranged to be mounted on andaxially keyed relative to said shaft; a hollow cylinder adapted tosurround said shaft; an annular ring surrounded by the hollow cylinderand axially movable, said annular ring being structured and arranged,during axial movement, to adjust a relative angular position of thehollow cylinder and the shaft; a retaining screw and a retaining washerfor locking the hollow cylinder and the shaft in their adjusted relativeangular position after the coupling device has been mounted on the shaftby pressing the retaining washer against a front face of the hollowcylinder with the retaining screw, and the hollow cylinder against thehub; assembly means for assembling the coupling device and the retainingwasher as the subassembly at least prior to mounting of the couplingdevice on the shaft; the subassembly further comprising for the axialdisplacement of the annular ring, an annular drive screw carrying ahelical thread which cooperates with a helical thread on a surfacewithout splines of either the hollow cylinder or the hub, that carriesthere at least one spline, said annular ring being coupled intranslation into said annular drive screw.
 24. The subassembly accordingto claim 23, further comprising a transverse abutment which limits theaxial travel of the annular drive screw.
 25. The subassembly accordingto claim 23, wherein the annular drive screw is not strictly circularwhen at rest.
 26. The subassembly according to claim 23, wherein theannular drive screw is slit and its thread is a single thread startingfrom one side of said slit and ending at the other side.
 27. Thesubassembly according to claim 23, wherein ends of threaded areas arecircumferentially in line with or at a distance from helical flanks of arim adapted to be pressed against the hub and being on a radius at leastequal to the radius of a thread root.
 28. The subassembly according toclaim 27, wherein the ends are inclined to said flanks.